Technical Field
The present disclosure relates in general to a high voltage semiconductor device, and more particularly to a high voltage semiconductor device having a high breakdown voltage and a low resistance.
Description of the Related Art
In recent decades, there is an ongoing drive toward the downscaling of dimensions of semiconductor structures while improving the speeds, efficiencies, densities and unit costs thereof simultaneously. For high voltage (HV) or Ultra high voltage (UHV) semiconductor device (such as metal-oxide-semiconductor (MOS) device), metal lines for connecting devices in silicon processes may induce the turn-on of parasitic field devices when these metal lines pass through specific regions. In other words, while MOSFETs are under high voltage operations, the maximum operating voltages thereof may be limited by turned on threshold voltages (Vth) of the parasitic field devices and might be lower than the breakdown voltages of MOSFETs.
However, there has been always a trade-off between these two important factors, the increase of the breakdown voltages and the decrease of the resistance. Therefore, researchers have been working on the manufactures of high voltage MOSFETs with high breakdown voltages and low resistances.